Seizure Disorder vs. Epilepsy: What's the Difference?

My mom and I were talking about my seizures the other day. Neither of us are medical professionals. She referred to my seizures as “seizure disorder.” I said, “You mean epilepsy?” “You don’t have epilepsy because your seizures are based on your brain structure.” The brain structure part is true, I’ve had several MRIs proving this. But is this true? If seizures are caused by your brain structure, is it technically not epilepsy? I thought epilepsy simply meant you’ve had more than one seizure in your life. I.E., chronic seizures, regardless of the cause. Who’s right, her or me?